The present invention relates to alkoxy-functional one-component RTV silicone rubber compositions and more particularly, the present invention relates to alkoxy-functional one-component RTV silicone rubber compositions having therein novel scavengers and novel integrated cross-linker, scavenger compounds.
The earliest one-component RTV silicone rubber compositions were acyloxy-functional; see for instance, Bruner, U.S. Pat. No. 3,035,016 and Ceyzeriat, U.S. Pat. No. 3,133,891. These compositions in a simple form, comprise a silanol end-stopped diorganopolysiloxane polymer, an acetoxy-functional cross-linking agent and a condensation catalyst. It was disclosed in subsequent patents that various other ingredients could be incorporated into such compositions, such as, for instance, fillers, plasticizers, adhesion promoters and so forth. As work progressed in the area, various other RTV silicone rubber compositions (RTV in this application shall refer to room-temperature vulcanizable) with different functionalities were developed. Thus, ketoxime-functional, amine-functional, aminoxy-functional and alkoxy-functional, one-component RTV silicone rubber compositions were developed. For amine-functional RTV silicone rubber compositions, see for instance, Nitzsche, et al, U.S. Pat. No. 3,032,528. An alkoxy-functional one-component RTV silicone rubber composition is to be found in Beers, U.S. Pat. No. 4,100,129.
Acetamide silyl compounds were also developed as can be seen in the disclosure of Klebe, U.S. Pat. No. 3,488,371. In the continuation of such development there were developed amide-functional one-component RTV silicone rubber compositions as can be seen from the disclosure of Golitz, U.S. Pat. No. 3,417,047. Other disclosures in this area are, for instance, Toporcer, U.S. Pat. Nos. 3,776,934 and 3,776,933.
There were also some disclosures in the area of the use of acetamide or diacetamide-functional silanes as chain extenders in one-component RTV silicone rubber compositions having various functionalities as can be seen from the disclosure of U.S. Pat. No. 4,020,044 and U.S. Pat. No. 3,817,909. Recently, there have been further developments in the area, for instance, see the disclosures of Mitchell, et al, U.S. Pat. No. 4,252,977 and Beers, U.S. Pat. No. 4,323,489 which disclose the production of novel acetamide silane compounds and the use of such novel acetamide compounds as chain extenders in the production of aminoxy and ketoxime-functional one-component RTV silicone rubber compositions. It was stated in these latter patents and particularly, U.S. Pat. No. 4,323,489 that as a result of the use of an acetamide chain-extender silane compound, there resulted an extremely low-modulus one-component RTV silicone rubber composition.
As stated previously, alkoxy-functional onecomponent RTV silicone rubber compositions were also developed, as can be seen by the disclosure of Beers, U.S. Pat. No. 4,100,129. Generally, such compositions comprise an alkoxy-functional silane as a cross-linking agent, a silanol-terminated diorganopolysiloxane base polymer and a titanium chelate catalyst as the condensation catalyst. These compositions had various advantages such as, that they were essentially non-corrosive; that is, they gave off substantially non-corrosive by-products and did not give off a pungent odor as did some of the other compositions. They were also relatively inexpensive to produce as compared to some of the other RTV compositions disclosed above. However, these compositions had disadvantages in that they did not have as fast a cure-rate as would be desirable and did not have very good shelf-stability. By shelf-stability, it is meant that the composition after being stored for periods of time of 6 months or more, would tend to cure slowly or in some cases, not at all. It was hypothesized that such degradation in the shelf-stability of the composition or the cure rate of the composition resulted from the fact that the moisture in the composition and even slight amounts of moisture or unbonded hydroxy groups would attack the alkoxy-groups in the base polymers, hydrolyzing them and replacing the polyalkoxy groups with mono-alkoxy groups. Such monoalkoxy endcapped diorganopolysiloxane polymers when they were cured by being exposed to atmospheric moisture, would react very slowly, if at all. As can be imagined, this resulted in a slow-curing composition. The longer the composition was stored prior to use after manufacture, the greater was the likelihood that a large amount of mono-alkoxy groups would be formed via hydrolysis by unbonded hydroxy groups; and thus, the greater was the likelihood that the composition would have an unsatisfactory cure rate. As a matter of fact, tests seem to indicate that the shelf-stability or the cure rate of such compositions were affected even after periods of storage as small as two weeks; see White et al, U.S. Pat. No. 4,395,526. Various attempts were made to improve the shelf-stability of the Beers, U.S. Pat. No. 4,100,129, composition with varying degrees of success.
It was the invention of White, et al, U.S. Pat. No. 4,395,526, to utilize novel scavengers and novel integrated cross-linker, scavengers in such alkoxy-functional one-component RTV silicone rubber ccmpositions such as to react with unbonded hydroxy groups so as to tie up such hydroxy groups so that the unbonded hydroxy groups would not react with the alkoxy groups in the terminal positions of the base polymers in the compositions and thus, degrade them. It is disclosed in White, et al, U.S. Pat. No. 4,395,526, that these scavenging, leaving groups can be various types of acetamide-functional hydrolyzable leaving groups. Other types of acetamide-functional compounds useful as scavengers and integrated cross-linker, scavengers is further disclosed in Chung, U.S. Pat. No. 4,424,157.
It is now the purpose of the present application to disclose further acetamide functional silanes and siloxanes which can be used as integrated cross-linker, scavengers and scavengers in alkoxy-functional one-component RTV silicone rubber compositions so that such compositions can be shelf-stable and have a sufficiently rapid cure rate.
It is one object of the present invention to provide for shelf-stable fast-curing alkoxy-functional one-component RTV silicone rubber compositions having novel integrated cross-linker and scavenger compounds therein.
It is another object of the present invention to provide for shelf-stable one-component alkoxy-functional RTV silicone rubber compositions having novel acetamide functional integrated cross-linker, scavengers therein.
It is yet an additional object of the invention to provide for an alkoxy-functional one-component RTV silicone rubber composition having novel acetamide functional silanes and siloxanes as integrated cross-linkers and scavengers therein.
It is yet a further object of the present invention to provide a process for producing alkoxy-functional one-component RTV silicone rubber composition having novel integrated cross-linker scavengers and scavenger compounds therein.
These and other objects of the present invention are accomplished by the disclosure below.